Conventionally, magnetic resonance imaging apparatuses include a gradient magnetic field power supply that supplies electric power to a gradient coil that generates a gradient magnetic field in an imaging space. For example, the gradient magnetic field power supply includes a plurality of switching circuits that are cascade-connected, and each of the switching circuits outputs a predetermined pulse voltage. Each of the switching circuit has a predetermined number of switching elements, and the switching elements mutually perform switching operation, to output a pulse voltage in accordance with the waveform of a current flowing through the gradient coil. It is known that a switching loss occurs when each of the switching elements performs switching operation as described above.